Physical and Biological Hazards of the Workplace, 3rd Edition

Chapter 15MICROWAVE, RADIOFREQUENCY, and EXTREMELY LOW-FREQUENCY ENERGY

Richard Cohen and Peter H. Wald

Microwaves (MW) include that portion of the electromagnetic spectrum between 300 megahertz (MHz) and 300 gigahertz (GHz). Radiofrequency (RF) radiation comprises that portion of the electromagnetic energy spectrum in which wave frequency varies from 3 kilohertz (kHz) to 300 MHz. Extremely low-frequency (ELF) radiation includes frequencies <3 kHz; it commonly refers to radiation associated with electric power generation and transmission. This chapter will address MW, RF, and ELF radiation.

MICROWAVE AND RADIOFREQUENCY RADIATION

Occupational setting

The four types of devices that generate RF and MW energy are power grid tubes, linear beam tubes (klystrons), crossed-field devices, and solid-state devices. Sources of RF and MW energy can operate in three modes: continuous, intermittent, and pulsed. The continuous mode is used in some communication devices, the intermittent mode is used in heating devices, while the pulsed mode is used in radar and digital communication.

MW energy can be transmitted from the generating device through a wave guide or through a transmission line to an applicator or antenna. Microwaves are used to transmit signals in telecommunications, navigation, radar, and broadcasting (i.e., radio and television); they can also be used to produce heat in industrial and home microwave ovens and dielectric heaters (i.e., heaters used to heat electrically nonconductive ...